An employee who misuses a company computer with fraudulent intent is guilty of a crime, a federal appeals court has ruled, dismissing claims that its reading of the law would expose millions of Americans to prosecution for everyday workplace activities.

In a 2-1 decision Thursday, the Ninth U.S. Circuit Court of Appeals in San Francisco said federal law makes it a crime to violate an employer's restrictions on computer use for fraudulent purposes, as long as the employer has made those limits clear to its staff.

The court insisted it was not reading the law too broadly.

"We do not dismiss lightly (a defense) argument that our decision will make criminals out of millions of employees who might use their work computers for personal use, for example, to access their personal e-mail accounts or to check the latest college basketball scores," said Judge Stephen Trott in the majority opinion.

But he said those cases would be screened out by the law's requirements of proof that the employee acted with an "intent to defraud" and accomplished that purpose by misusing the computer.

In dissent, U.S. District Judge Tena Campbell of Utah, sitting by temporary assignment, said the majority's interpretation would also apply to another section of the same law that does not require proof of fraudulent intent.

She said the ruling allows prosecution of "any person who obtains information from any computer connected to the Internet, in violation of her employer's computer use restrictions." The court reinstated charges against David Nosal, a former manager at the Redwood City office of Korn/Ferry International, the world's largest executive search firm. Prosecutors said Nosal, after resigning in 2004, enlisted three employees to tap the computer system for customer lists and other secret information to help him start his own business.

Nosal has denied wrongdoing. A federal judge ruled last year that Nosal could not have violated the law's ban on "exceeding authorized access" to a company computer because his alleged co-conspirators were authorized to use the computer system.

But the appeals court said an employee who is authorized to use the computers, but knowingly violates company use restrictions, can be prosecuted.